Câu 8:

Biết $\int\limits_{1}^{2}{f\left( x \right)\text{d}x=6}$, $\int\limits_{2}^{5}{f\left( x \right)\text{d}x=1}$, tính $I=\int\limits_{1}^{5}{f\left( x \right)\text{d}x}$.